Method and apparatus for particle image analysis using flow cell

A sample is flowed through a flow cell, the passage of particles is detected by a laser light beam, a flash lamp is turned on in response to the detection, still images of the particles are picked up by a TV camera, and the images are image-processed. A particle detection unit adjusting unit calculates the anticipated number of image-processed particles from the total number of detected particles, compares it with the number of actually image-processed particles, and changes a particle detection condition such that the calculated value is equal to the actual measurement value. In actual sample measurement, an operation condition of the apparatus can be determined and measurement result can be corrected using those parameters.